摘要:

The refractive index of insulators may be changed by ion implantation and for several crystalline materials such as quartz, LiNbO3and LiTaO3this is thought to be associated with the production of regions of high defect density or even amorphisation of the lattice. Analyses of the refractive index profiles using reflectivity and waveguide mode spacing have been compared. These reveal distinct differences in the profiles of n0and nefor LiNbO3and LiTaO3. These data will be discussed in terms of the contributions to the damage from electronic excitation and nuclear collision damage.

ISSN:0033-7579    

DOI:10.1080/00337578608206112

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Ion implantation with MeV4He+ions has been used by several workers to fabricate planar optical waveguides in LiNbO3. The process of fabrication of these waveguides includes a 30 min furnace anneal in oxygen to remove the radiation damage from the guiding layer and to replace oxygen lost during implantation. In this work a transient anneal schedule on LiNbO3was followed. The annealing time is reduced and the attenuation of these waveguides found to be an order of magnitude lower than identical waveguides annealed by conventional methods. Waveguides implanted with single energy ions with losses as low as 0.2 dB/cm at 0.633 μm have been produced.

ISSN:0033-7579    

DOI:10.1080/00337578608206113

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Optical waveguides may be formed in silica by an increase in refractive index resulting from a compaction of the glass network caused during radiation damage. An additional index enhancement had been ascribed to chemical changes during nitrogen implantation. The present work confirms this higher level of index enhancement of up to 4%. Measurements of the refractive index profile before and after annealing suggest that whereas electronically generated damage is annealed by 450°C, the changes in the region of the implanted nitrogen are stable. In the region of maximum nitrogen concentration the presence of a glass phase resembling silicon oxynitride is proposed. However a comparison of the refractive index profile with computer simulations of impurity and defect profiles suggests that radiation damage induced by nuclear collisions contributes to the refractive index profile even in the annealed samples.

ISSN:0033-7579    

DOI:10.1080/00337578608206114

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Luminescence produced during ion beam implantation of LiNbO3has been shown to be a sensitive measure of the defect state of the crystals. The spectra may be resolved into a number of component bands which differ as a result of extrinsic impurities, intrinsic defects and manufacturer. The spectra change during the ion implantation and are sensitive to the implantation temperature. Of particular note is evidence for the production of free lithium metal and the data are also interpreted to show a difference in titanium location for dopants introduced during the growth process from those added subsequently by thermal diffusion.

ISSN:0033-7579    

DOI:10.1080/00337578608206115

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

In order to gain a better understanding of the behaviour of optical waveguides created by the implantation of helium ions into Y-cut LiNbO3, 50 keV He ion-induced lattice disorder and refractive index changes have been studied with the aid of RBS channelling and Brewster angle measurements. It is found that changes in refractive index cannot be explained in terms of lattice disorder alone and it is suggested that Li-outdiffusion plays a significant role.

ISSN:0033-7579    

DOI:10.1080/00337578608206116

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Initial data are reported for X-ray induced luminescence and thermoluminescence from a number of compounds of interest for electro-optic applications. The materials used were LiNbO3, LiTaO3, Ba2NaNb5O15and LiIO3. In general the signals were weak with the strongest features of both radio-luminescence and thermoluminescence occurring in the temperature range 30 to 100 K. The techniques have revealed a number of defect states in each of the materials.

ISSN:0033-7579    

DOI:10.1080/00337578608206117

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Current development of the research of radiation damage in ionic solids is reviewed. Emphasis is placed on the correlation between elementary radiation damage processes and the atomic and electronic structures of the materials. Both the radiation damage induced by electronic excitation and by elastic collision are treated. For the former two crucial processes, the self-trapping of excitons and the formation of stable Frenkel pairs from the self-trapped excitons in several materials, is discussed in terms of the structures of materials. Deficiency in the available data on the knock-on threshold energies are pointed out. Available information of Frenkel pairs produced by electronic and elastic encounters is surveyed. Possible models of defect clustering are summarized and existing information on clustering is discussed on their basis.

ISSN:0033-7579    

DOI:10.1080/00337578608206118

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Lattice disorder produced by ion implantation of CdS crystals with Bi+, Kr+, Ar+and Ne+has been studied using RBS/Channeling and Transmission Electron Microscopy (TEM). Channeling measurements of the damage, as represented by an apparent number of displaced atoms, ND, obtained from the surface peak and by the change in the dechanneling, level, ΔXmin, behind the surface peaks, have been studied as a function of channeling direction (c- anda-axis), He+beam energy (0.8–2.8 MeV), implant and analysis temperature (50 K and 300 K). The channeling measurements are consistent with the TEM observations that the damage is primarily in the form of interstitial type dislocation loops which predominantly lie with a Burgers vector parallel to thea-axis. Both techniques confirm that implantation does not produce an amorphous layer in CdS.

ISSN:0033-7579    

DOI:10.1080/00337578608206119

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

In alkali halides, interstitial halide atoms are created under ionizing radiations at room temperature and their stabilization is known to play an important role in the coloration process. In alkali iodides such as KI, the coloration efficiency is known to be drastically increased by the addition of divalent cations. By means of Raman experiments, we describe the different stages of formation of V-type defects in the case of Ca+2doped KI. By using traps like TI+cations, we show that the interstitial stabilization is different and does not lead to the formation of polyiodides as observed in KI:Ca+2.

ISSN:0033-7579    

DOI:10.1080/00337578608206120

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Optical absorption spectra in the range 2 eV to 12 eV are presented for lithium fluoride crystals implanted with rare gas ions argon and neon of energy 100 keV. F- and M-centres are produced by both types of ion at low doses of the order of 1016cm−2. At higher doses (about 3 × 1016cm−2for argon and 3 × 1017cm−2for neon) a broad absorption band is produced in the same spectral region near 2.38 eV (520 nm) by both types of ion. This band is colloidal in nature and is attributed to intrinsic lithium colloids. The growth of F-, M- and V3-centres is examined in the light of lithium colloid development and a consistent mechanism is proposed. The possible role of the dose rate and the implanted rare gases is considered. The defect structures observed by absorption in the vacuum ultraviolet are discussed.

ISSN:0033-7579    

DOI:10.1080/00337578608206121

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor